In FY2018, we continued to examine the disparities in tobacco use in the US population. Using the data from the Florida Youth Tobacco Survey, we examined the variations in cigarette use and related social environment between youth livening in the metropolitan and non-metropolitan areas. We found that compared to youth living in the metropolitan areas, youth living in the non-metropolitan areas are more likely to smoke cigarettes and smoking higher number of cigarettes. They are also more likely to perceive adult smoking as an acceptable behavior, be offered a cigarette by parents, live with tobacco users and in homes where tobacco use is allowed, and exposure to tobacco advertising. These findings indicate that addressing the tobacco-related social environment maybe a promising pathway to reduce rural-urban disparities in tobacco use. Using data from the National Adult Tobacco Survey, we examined the proportion of young adult smokers who are in the precontemplation stage for smoking cessation. We found that 59% of young adult smokers are in this stage (i.e., not planning to quit smoking in the next six months). We did not observe significant variation by income and education but observed non-Hispanic Black young adult smokers are less likely to be in the precontemplation stage. These findings suggest that smokers of racial/ethnic minorities and lower socioeconomic status are as likely as their non-Hispanic White and higher socioeconomic status counterparts to quit smoking. Finding ways to motiving these populations to quit smoking may reduce tobacco use disparities in the US. We continued to discover the potential impact of e-cigarette use on health and health disparities. Working with collaborators from the University of Hawaii to analyze the Hawaii Youth Risk Behavior Survey, we found that e-cigarette use was more common among youth with asthma than those without asthma. We also observed asthma is more common among Blacks, Native Hawaiians or other Pacific Islanders, and Filipinos than Asians and Whites. Working with collaborators at the George Washington University and Florida Department of Health, we analyzed the Florida Youth Tobacco Survey data to examine the beliefs associated with e-cigarettes among Florida youth. We found that compared to committed never tobacco users, those who are at-risk or currently using e-cigarettes perceived e-cigarettes as less harmful and providing more social benefits (e.g., having more friends). This is the first study to examine the perceived benefits of e-cigarettes among youth. Using the data from the same survey, we conducted the first study to examine the exposure to secondhand smoking and secondhand e-cigarette vapor exposure among youth. We observed 42% of Florida youth are exposed to secondhand smoke, and 29% are exposed to secondhand e-cigarette vapor exposure. We found that those living in trailer/mobile home and townhouse/duplex are more likely than those living stand-alone homes to be exposure to secondhand smoke. We also learned that having home smoking ban reduces the likelihood for youth to be exposed to secondhand smoke and secondhand e-cigarette vapor. This signals that voluntary home tobacco use ban can protect youth from these exposures. Together with a multi-agencies and universities research team, we used the Population Assessment of Tobacco and Health (PATH) Study to examine the transition in e-cigarette use among adults. We found that over time, about half of the adult e-cigarette users discontinued e-cigarette use. Among smokers who also use e-cigarettes, 88% continue to smoke cigarettes over time. This suggests limited utility for e-cigarettes to reduce the prevalence of smoking at the population level. We further investigated the factors associated with tobacco use and tobacco use disparities. Working with the PATH Study Team, we examined if receptivity to tobacco advertising is associated with progression in tobacco product use among youth and young adults. We found that receptivity increased from 44% at ages 12-14 to 63% at ages 22-24. We also found that receptivity is positively associated with subsequent progression of tobacco product use. Additionally, we examined whether direct-to-consumer tobacco coupons influence changes in smoking behaviors among US adults. Using the PATH Study, we found lower socioeconomic status adults were more likely to receive these coupons, and receipt of these coupons promoted progression in cigarette smoking and hindered long-term smoking cessation. Furthermore, we investigated the phenomenon of online tobacco marketing engagement among youth. Using the PATH Study data, we found the engagement with online tobacco marketing increased over time among youth, and such engagement predicted subsequent progression of tobacco use behavior in this population. Overall, our research shows that tobacco marketing is still influencing tobacco use and related disparities. A new objective is to examine the reciprocal relationships between social determinants of health and tobacco use. Using the data from the NEXT Generation Health Study, we found that youth who smoked during high school are less likely to subsequent enroll in a 4-year college, supporting the argument that tobacco use during adolescence can have long-lasting impact on social determinants of health. Through collecting tobacco-free campus information about the post-secondary educational institutions the participants attended, we found that less than half of these institutions have comprehensive tobacco-free campus policy, and the prevalent is significantly lower among for-profit institutions that are disproportionately attended by minority students and lower socioeconomic status young adults. These findings support the argument that social determinants of health influence ones likelihood of being covered by tobacco control policies. In FY2018, we had 16 publications in peer-reviewed journals and 23 presentations at various national and international scientific conferences.